Faculty Profiles - SAITO, Nagahiro

Papers - SAITO, Nagahiro

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Preparation and wettability examinations of transparent SiO<inf>2</inf> binder-added MgF<inf>2</inf> nanoparticle coatings covered with fluoro-alkyl silane self-assembled monolayer

Murata T., Hieda J., Saito N., Takai O.

Applied Optics Vol. 51 ( 13 ) page： 2298 - 2305 2012.5

Language：English Publishing type：Research paper (scientific journal) Publisher：Applied Optics

SiO2-added MgF2 nanoparticle coatings with various surface roughness properties were formed on fused silica-glass substrates from autoclaved sols prepared at 100-180 °C. To give it hydrophobicity, we treated the samples with fluoro-alkyl silane (FAS) vapor to form self-assembled monolayers on the nanoparticle coating and we examined the wettability of the samples. The samples preserved good transparency even after the FAS treatment. The wettability examination revealed that higher autoclave temperatures produced a larger average MgF2 nanoparticle particle size, a larger surface roughness, and a higher contact angle and the roll-off angle. © 2012 Optical Society of America.

DOI： 10.1364/AO.51.002298

Active species generated by a pulsed arc electrohydraulic discharge plasma channel in contaminated water treatments

Li O.L., Takeuchi N., He Z., Guo Y., Yasuoka K., Chang J.S., Saito N.

Plasma Chemistry and Plasma Processing Vol. 32 ( 2 ) page： 343 - 358 2012.4

Language：English Publishing type：Research paper (scientific journal) Publisher：Plasma Chemistry and Plasma Processing

Pulsed arc electrohydraulic discharge (PAED) direct plasma technique was applied for various types of contaminated water treatment. The experimental system consists of a spark-gap switch type pulse power supply (0.5 kJ/pulse) and a 3 L stainless steel reactor with eccentrically configured rod-to-rod electrodes. The current and voltage waveforms are fundamentally different for different conductivity water. Double pulse current discharges were observed for pond water with relatively higher conductivity (637 mS/m) while a single pulse current discharge was observed for lake water with relatively lower conductivity (78 mS/m). From the optical emission spectrum and UV dosimeters, UV-A, UV-B, excited molecules and radicals including N 2*, O, H, OH, O3 etc. were observed during the discharge period. Both optical emission and UV intensities in pond water are slightly lower than lake water. The decay time of the UV-A, N 2*, OH, H and O radicals were around 0.6 ms, where the discharge period ended around 0.4 ms. The results indicate that the radicals existed longer than the discharge period. The pH, dissolved oxygen and conductivity were changed during the course of PAED treatment. The ions and radicals such as H·, O·, H +, OH· etc. generated by PAED may cause alterations density decay time and the active species in water were present for a longer period. The reduction of total organic carbon (TOC) in pond water reached 80% after 5 min of PAED treatment Based on local thermal plasma equilibrium (LTE) model, LTE thermal plasma chemical composition model for 1 mol water vapour was used to compare to present experiments. PAED discharge in contaminated pond water generated peak concentration of OH = 28% and O 2H = 0.012% mol in gas-phase and migrated to water-phase via gas-liquid interfaces generated by arc and micro-bubbles to form more stable O3, H2O 2, H2 and O 2. The model suggested that the reduction of TOC occurred in gas/plasma phases or liquid-phase side of gas liquid interfaces. © Springer Science+Business Media, LLC 2011.

DOI： 10.1007/s11090-011-9346-8

High sensitive detection of volatile organic compounds using superhydrophobic quartz crystal microbalance

Andreeva N., Ishizaki T., Baroch P., Saito N.

Sensors and Actuators, B: Chemical Vol. 164 ( 1 ) page： 15 - 21 2012.3

Language：English Publishing type：Research paper (scientific journal) Publisher：Sensors and Actuators, B: Chemical

A quartz crystal microbalance (QCM) chemical sensor coated with superhydrophobic film for detecting volatile organic compounds (VOCs) such as formaldehyde and toluene under ambient conditions was developed. The superhydrophobic film was deposited by means of microwave plasma enhanced chemical vapor deposition (MPECVD). The sensitivities of QCM sensor coated with superhydrophobic film to VOCs such as formaldehyde and toluene were investigated under ambient conditions. The sensitivity of the sensor to formaldehyde and toluene was considerably improved by the superhydrophobic surface modification. The surface modification promoted microscopic texturing to the film surface and thus increased the effective specific surface area of the sensor for the adsorption of formaldehyde and toluene. In addition, the adsorption of water molecules was minimized due to the superhydrophobic film deposited on the sensor surface, thus promoting the preferential adsorption of formaldehyde and toluene molecules on the QCM sensor coated with superhydrophobic film, compared to the conventional QCM sensor. Moreover, the adsorption mechanisms of formaldehyde-water and toluene-water molecules to the superhydrophobic film were discussed. © 2012 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.snb.2012.01.051

Preparation of low molecular weight chitosan using solution plasma system

Prasertsung I., Damrongsakkul S., Terashima C., Saito N., Takai O.

Carbohydrate Polymers Vol. 87 ( 4 ) page： 2745 - 2749 2012.3

Language：English Publishing type：Research paper (scientific journal) Publisher：Carbohydrate Polymers

The solution plasma system was introduced to treat chitosan solution in order to prepare low molecular weight chitosan. The plasma treatment time was varied from 0 min to 300 min. The plasma-treated chitosan was characterized including viscosity, molecular weight by GPC, and chemical characteristics by FT-IR. The results showed that after treated with plasma for 15-60 min, the viscosity of chitosan solution and apparent molecular weight of chitosans were remarkably decreased, compared to those of untreated sample. Longer treatment time had less effect on both viscosity and molecular weight of samples. Eventually, long treatment time (>180 min) showed no influence on both viscosity and apparent molecular weight. This suggested that the degradation process of chitosan occurred during plasma treatment. FTIR analysis revealed that chemical structure of chitosan was not affected by solution plasma treatment. TOF-MS results showed that chitooligosaccharides with the degree of polymerization of 2-8 were also generated by solution plasma treatment. The results suggested that solution plasma system could be a potential method for the preparation of low molecular weight chitosan and chitooligosaccharides. © 2011 Elsevier Ltd.

DOI： 10.1016/j.carbpol.2011.11.055

Growth and characterization of highly c-axis textured SrTiO <inf>3</inf> thin films directly grown on Si(001) substrates by ion beam sputter deposition

Panomsuwan G., Cho S., Saito N., Takai O.

Crystal Research and Technology Vol. 47 ( 2 ) page： 187 - 194 2012.2

Language：English Publishing type：Research paper (scientific journal) Publisher：Crystal Research and Technology

Highly c-axis textured SrTiO 3 (STO) thin films have been directly grown on Si(001) substrates using ion beam sputter deposition technique without any buffer layer. The substrate temperature was varied, while other parameters were fixed in order to study effect of substrate temperature on morphology and texture evolution of STO films. X-ray diffraction, pole figure analysis, atomic force microscope, and high-resolution electron microscopy were used to characterize and confirm quality and texture of the STO films. The experimental results show that optimum substrate temperature to achieve highly c-axis textured films is at 700 °C. The full width at half maximum (FWHM) of 002 STO was found to be 2° and fraction of (011) orientation was as low as 1%. The surface morphology was Volmer-Weber growth mode with a small roughness ∼1 nm. The lowest leakage current density (5.8 μA/cm 2 at 2 V) and the highest dielectric constant (Îμ STO ∼ 98) were found for highly c-axis textured films grown at 700 °C. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

DOI： 10.1002/crat.201100573

Rapid synthesis and structural characterization of well-defined gold clusters by solution plasma sputtering

Hu X., Cho S., Takai O., Saito N.

Crystal Growth and Design Vol. 12 ( 1 ) page： 119 - 123 2012.1

Language：English Publishing type：Research paper (scientific journal) Publisher：Crystal Growth and Design

Ultrafine metal nanoparticles of a few nanometers in diameter exhibit size-dependent photonic and electric properties that are of interest for applications such as biosensors, catalysts, optics, and electronics. Chemical approaches and vacuum metal-vapor-condensation physical techniques were used to successfully synthesize gold nanoparticles. While it is difficult to obtain monodisperse and small sized gold nanoparticles without any reductant and polymer stabilizer or under vacuum conditions, in the present study, multiply twinned and near monodisperse gold clusters of diameter less than 2.0 nm were successfully fabricated for the first time by solution plasma sputtering in liquid nitrogen (LN 2) without any chemical additions (such as reductant and polymer stabilizer). Gold clusters formed in several microseconds simultaneously with solution plasma sputtering in an open system under atmospheric pressure. Gold clusters are identified to be well crystalline and multitwin-particles (MTPs) by high-resolution transmission electron microscopy. No surface plasmon resonance band was detected in the gold cluster aqueous solutions. Such MTPs with special corners and edges would be beneficial for tailoring catalytic properties at the nanoscale. The solution plasma sputtering method will have potential application in the future in the design and mass preparation of various multifunctional metal clusters. © 2011 American Chemical Society.

DOI： 10.1021/cg2008528

Effect of Sn<sup>4+</sup> additives on the microstructure and corrosion resistance of anodic coating formed on AZ31 magnesium alloy in alkaline solution

Salman S.A., Kuroda K., Saito N., Okido M.

Magnesium Technology page： 241 - 245 2012

Language：English Publishing type：Research paper (scientific journal) Publisher：Magnesium Technology

Magnesium is the lightest structural metal with high specific strength and good mechanical properties. However, poor corrosion resistance limits its widespread use in many applications. Magnesium is usually treated with chromate conversion coatings. However, due to changing environmental regulations and pollution prevention requirements, a significant push exists to find new, alternative for poisonous Cr6+. Therefore, we aim to improve corrosion resistance of anodic coatings on AZ31 alloys using low cost non-chromate electrolyte. Anodizing was carried out in alkaline solutions with tin additives. The effect of tin additives on the coating film was characterized by SEM and XRD. The corrosion resistance was evaluated using anodic and cathodic polarizations and electrochemical impedance spectroscopy (EIS). Corrosion resistance property was improved with tin additives and the best anti-corrosion property was obtained with addition of 0.03 M Na 2SnO3.3H2O to anodizing solution.

DOI： 10.1002/9781118359228.ch45

Size-controlled gold nanoparticles synthesized in solution plasma

Bratescu M.A., Cho S.P., Takai O., Saito N.

Journal of Physical Chemistry C Vol. 115 ( 50 ) page： 24569 - 24576 2011.12

Language：English Publishing type：Research paper (scientific journal) Publisher：Journal of Physical Chemistry C

Size-controlled gold nanoparticles (NPs) have been synthesized using an electrical discharge in a liquid environment, termed solution plasma processing (SPP). The gold NPs exhibit sizes from 1 to 2 to 10 nm when the solution pH was adjusted in the range from 12 to 3, respectively. The chemical environment surrounding the gold NPs depends on the preparation conditions and determines the electrostatic interaction among the nanoparticles, which alters their final size. Information obtained from XPS analysis, ToF-SIMS mass spectra, and UV-vis absorption spectroscopy were consistent and demonstrate that the gold NPs are partially oxidized on the surface, when synthesized in a pH 12 solution, and remain surrounded by gold chloride compounds when synthesized in a pH 3 solution. Plasma diagnostics shows that a high electron density contributes to generating a larger number of hydrogen radicals, which represent the main component in the reduction process of the gold ion into the neutral form. © 2011 American Chemical Society.

DOI： 10.1021/jp207447c

Low-temperature fabrication of bunch-shaped ZnO nanowires using a sodium hydroxide aqueous solution

Hu X., Masuda Y., Ohji T., Saito N., Kato K.

Journal of Nanoscience and Nanotechnology Vol. 11 ( 12 ) page： 10935 - 10939 2011.12

Language：English Publishing type：Research paper (scientific journal) Publisher：Journal of Nanoscience and Nanotechnology

Bunch-shaped ZnO nanowires film was successfully fabricated by the forced-hydrolysis-initiatednucleation of anhydrous zinc acetate in an aqueous solution of zinc acetate and sodium hydroxide at low temperature. X-ray diffraction and a field emission scanning electron microscope clarified their formation mechanism and morphology development. The morphology was controllable by adjusting the solution temperature and deposition time. ZnO nanowires obtained at 65 °C for 6 h have a high aspect ratio of about 106. The smaller diameter with higher aspect ratio of ZnO nanowires, the easier the formation of bunch shapes by the capillary force during the drying process. This fabrication technique indicated that bunched ZnO film was prepared at low cost, and fittable to low heat-resistance substrates such as a polymer substarte. Copyright © 2011 American Scientific Publishers All rights reserved.

DOI： 10.1166/jnn.2011.4045

Cell adhesion behaviors on polyethylene terephthalate surface modified by surface-wave plasma-initiated graft polymerization

Ishizaki T., Andreeva N., Saito N.

Technical Proceedings of the 2011 NSTI Nanotechnology Conference and Expo, NSTI-Nanotech 2011 Vol. 1 page： 437 - 440 2011.11

Language：English Publishing type：Research paper (scientific journal) Publisher：Technical Proceedings of the 2011 NSTI Nanotechnology Conference and Expo, NSTI-Nanotech 2011

Hydrophilic modification of polyethylene terephthalate (PET) was successfully achieved by surface wave plasma treatment followed by graft polymerization with acrylic acid (AA) monomer. The graft reaction was confirmed by water contact angle measurements and X-ray photoelectron spectroscopy (XPS). 3T3 fibroblast cells were cultured on the AA-modified PET surface. The protein adsorption behaviors were also investigated using an optical waveguide spectroscopy.

Microstructural characterization of gold nanoparticles synthesized by solution plasma processing

Cho S., Bratescu M., Saito N., Takai O.

Nanotechnology Vol. 22 ( 45 ) 2011.11

Language：English Publishing type：Research paper (scientific journal) Publisher：Nanotechnology

Microstructural characteristics of gold nanoparticles (Au NPs) fabricated by solution plasma processing (SPP) in reverse micelle solutions have been studied by high-resolution transmission electron microscopy (HRTEM). The synthesized Au NPs, with an average size of 6.3 1.4nm, have different crystal characteristics; fcc single-crystalline particles, multiply twinned particles (MTPs), and incomplete MTPs (single-nanotwinned fcc configuration). The crystal structure characteristics of the Au NPs synthesized by the SPP method were analyzed and compared with similar-size Au NPs obtained by the conventional chemical reduction synthesis (CRS) method. The TEM analysis results show that the Au NPs synthesized by the CRS method have shapes and crystal structures similar to those nanoparticles obtained by the SPP method. However, from the detailed HRTEM analysis, the relative number of the Au MTPs and incomplete MTPs to the total number of the Au NPs synthesized by the SPP method was observed to be around 94%, whereas the relative number of these kinds of crystal structures fabricated by the CRS method was about 63%. It is most likely that the enhanced formation of the Au MTPs is due to the fact that the SPP method generates highly reaction-activated species under low environmental temperature conditions. © 2011 IOP Publishing Ltd.

DOI： 10.1088/0957-4484/22/45/455701

Wettability characterization of transparent MgF<inf>2</inf> nanoparticle coatings with SiO<inf>2</inf> binder covered with fluoroalkylsilane self-assembled monolayers

Murata T., Hieda J., Saito N., Takai O.

Journal of Sol-Gel Science and Technology Vol. 60 ( 2 ) page： 125 - 130 2011.11

Language：English Publishing type：Research paper (scientific journal) Publisher：Journal of Sol-Gel Science and Technology

SiO2-added MgF2 nanoparticle coatings with various surface roughness properties were formed on silica-glass substrates from autoclaved sols prepared at 100-180 °C. The samples were exposed to fluoro-alkyl silane (FAS) vapor to give hydrophobicity. All nanoparticle samples before FAS treatment had transmittances higher than 93% and such values were preserved even after FAS treatment. We examined root mean square roughnesses of the nanoparticle coatings with a Scanning Probe Microscope. We also examined their static and dynamic wettabilities with a contact angle meter and calculated their adhesive energies and surface free energies (SFEs). The surface roughness of the nanoparticle coating increased with the increase of the autoclave temperature. In addition, higher autoclave temperature caused increases in the sliding angle and decreases in the SFE. Interestingly, the higher the contact angle was, the larger the sliding angle was, although smaller sliding angle was expected with a larger contact angle. © 2011 Springer Science+Business Media, LLC.

DOI： 10.1007/s10971-011-2566-9

Effect of the electrode work function on the water plasma breakdown voltage

Miron C., Bratescu M., Saito N., Takai O.

Current Applied Physics Vol. 11 ( 5 SUPPL. ) 2011.9

Language：English Publishing type：Research paper (scientific journal) Publisher：Current Applied Physics

Experimental studies on the plasma initiated in ultrapure water between pairs of tungsten and lanthanum hexaboride electrodes have been performed. The current - voltage characteristics showed the features of a spark discharge for the both types of electrodes used in the process. The breakdown voltage depended on the work function and on the surface morphology of the electrodes. The reactive species formed in the water plasma and their emission intensity depended on the electrode material. © 2011 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.cap.2011.04.005

Redox reactions in liquid plasma during iron oxide and oxide-hydroxide nanoparticles synthesis

Bratescu M., Saito N., Takai O.

Current Applied Physics Vol. 11 ( 5 SUPPL. ) 2011.9

Language：English Publishing type：Research paper (scientific journal) Publisher：Current Applied Physics

A new synthesis method of iron oxide and iron oxide-hydroxide nanoparticles by pulsed liquid plasma process is presented. The redox reaction rates in liquid phase depend on the relative number densities of oxygen and hydrogen atoms produced in plasma gas phase and on the injected energy per pulse. The oxidation rate was higher than the reduction one in both regimes of plasma operation as glow and arc discharge. An oxidation rate of 0.13 μg mL -1 s-1 and a reduction rate of 0.04 μg mL-1 s-1 of iron ion during the process were obtained when plasma operates in glow discharge regime. The α-Fe2O3 and β-FeO(OH) nanoparticles of 80 nm size with a rice-shape morphology can be rapidly synthesized using low energy injected in plasma. © 2011 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.cap.2011.06.007

Adhesion property of SiO<inf>x</inf>-doped Diamond-like Carbon Films Deposited on Polycarbonate by Inductively Coupled Plasma Chemical Vapor Deposition

Baek S.M., Shirafuji T., Saito N., Takai O.

Thin Solid Films Vol. 519 ( 20 ) page： 6678 - 6682 2011.8

Language：English Publishing type：Research paper (scientific journal) Publisher：Thin Solid Films

SiOx-DLC (diamond-like coating) films as candidates for protection coating of polymers were prepared by using a pulse-biased inductively coupled plasma chemical vapor deposition system with acetylene, tetramethylsilane and oxygen gasses. Effects of the gas composition and O 2 plasma pre-treatment on adhesion of the SiOx-DLC films were investigated. Adhesion strength of Si-DLC films (with 0% oxygen) was almost the same to that of undoped DLC films. By employing O2-plasma pre-treatment, adhesion strength of the Si-DLC films was considerably improved, while that of the undoped DLC films was not. The SiOx-DLC films with the carbon to oxygen (O/C) ratio of 0.15 showed adhesion strength as high as that of the Si-DLC films on the O2-plasma pre-treated substrate. However, further improvement of adhesion strength of the SiOx-DLC was not realized by employing the O2-plasma pre-treatment. On the other hand, the SiOx-DLC films showed favorable feature of high deposition rate and large optical band gap although higher O/C ratio (> 0.15) brought about poor adhesion strength of the films. © 2011 Elsevier B.V.

DOI： 10.1016/j.tsf.2011.04.080

Solution plasma for template removal in mesoporous silica: PH and discharge time varying characteristics

Pootawang P., Saito N., Takai O.

Thin Solid Films Vol. 519 ( 20 ) page： 7030 - 7035 2011.8

Language：English Publishing type：Research paper (scientific journal) Publisher：Thin Solid Films

The evaluation of the ability of solution plasma process, SPP, depending on the pH of the discharge solution and discharge time for template removal in mesoporous silica was described. In the synthesis of mesoporous silica, ternary surfactant system containing tri-block copolymer EO20PO 69EO20 (P123), sodium dodecylbenzene sulfonate (SDBS), and 1,1,2,2,3,3,4,4,4-nonafluoro-1-butyl sulfonate (NFBS) was chemically used for synthesis under acid condition via sol-gel method then SPP was employed for template removal. The ordered 2D hexagonal arrangement was observed by the evidence of high resolution TEM and the diffraction mode of X-ray. The efficiency of SPP depending on the pH of the discharge solution and discharge time was scientifically demonstrated as a function of BET surface area. In the case of pH dependence, it was achieved that the ability of template removal in acid and base solutions was clearly higher than those of such results in neutral solution. In the term of discharge time, moreover, the percentage of template removal comparing in the result of BET surface area increased as the increase in discharge time. © 2011 Elsevier B.V.

DOI： 10.1016/j.tsf.2011.01.213

Fabrication of transparent protective diamond-like carbon films on polymer

Baek S.M., Shirafuji T., Saito N., Takai O.

Japanese Journal of Applied Physics Vol. 50 ( 8 PART 2 ) 2011.8

Language：English Publishing type：Research paper (scientific journal) Publisher：Japanese Journal of Applied Physics

Si doped hydrogenated amorphous carbon (Si-DLC) films as a candidate protection coating for polycarbonate (PC) were prepared using a pulsebiased inductively coupled plasma chemical vapor deposition (ICP-CVD) system with a gas mixture of acetylene (C2H2) and tetramethylsilane [Si(CH3)4]. The effects of Si incorporation on the structure and optical properties of the Si-DLC films were investigated. In addition, plasma pretreatments with O2, N2, and Ar gases were carried out to enhance the adhesion strength of Si-DLC films on polycarbonate. Structural characterization through Raman and X-ray photoelectron spectroscopy (XPS) analyses showed that the incorporation of Si atoms in DLC films leads to an increase in the optical band gap (Eopt) with the formation of sp3 C-Si bonds. O2 plasma pretreatment improved the strength of adhesion of the Si-DLC films to polycarbonate, while Ar and N2 plasma treatments did not. This can be explained by the formation of an activated dense interfacial layer by O2 plasma pretreatment. © 2011 The Japan Society of Applied Physics.

DOI： 10.1143/JJAP.50.08JD08

Wettability of MgF<inf>2</inf> porous nanoparticle layers covered with fluoroalkylsilane self-assembled monolayer

Murata T., Hieda J., Saito N., Takai O.

Journal of the Ceramic Society of Japan Vol. 119 ( 1391 ) page： 591 - 594 2011.7

Language：English Publishing type：Research paper (scientific journal) Publisher：Journal of the Ceramic Society of Japan

MgF2 porous nanoparticle coatings with SiO2 binder were formed on glasssubstrates by solgel method. The samples were exposed to fluoro-alkyl silane (FAS) vapor and heated at 150°C to give water repellency. We measured surface roughnesses and static contact angles of water of the samples and examined the relation between surface roughnesses and contact angles. Scanning Probe Microscopy (SPM) confirmed that the FAS treatment had no effect on the surfaceroughness. In the autoclave temperature region of 100180° C, the higher the autoclave temperaturewas, the larger the surface roughness was. The sample prepared from the 100°C autoclaved sol had the minimum surface roughness of 4.1 nm and showed the minimum static contact angle of 115°. On the other hand, the sample prepared from the 180°C autoclaved sol had the maximum surface roughness of 9.5 nm and showed the maximum static contact angle of 134°. © 2011 The CeramicSociety of Japan.

DOI： 10.2109/jcersj2.119.591

Optical diagnostic of bipolar electrical discharges in HCl, KCl, and KOH solutions

Miron C., Bratescu M.A., Saito N., Takai O.

Journal of Applied Physics Vol. 109 ( 12 ) 2011.6

Language：English Publishing type：Research paper (scientific journal) Publisher：Journal of Applied Physics

In this work, the characteristics of the plasma generated in HCl, KCl, and KOH solutions were analyzed using electrical and optical diagnostic techniques. Electrical discharges were initiated between two tungsten electrodes. Current and voltage characteristics have shown the features of a spark discharge for all of the solutions used in the experiment. The reactive species identified in the optical emission spectra depended on the type of solution used to generate the plasma. The time evolution of the reactive species depended on the nature of the solution and on the polarity of the applied pulse. The absorption spectra of the OH radical (X2 → A2∑+) were acquired when the voltage pulses were applied to the electrodes, with the intensity being lower in the regions between the pulses. The OH radical density was highest for the HCl solution plasma (2 × 1017cm -3) when positive voltage pulses were applied to the electrodes. © 2011 American Institute of Physics.

DOI： 10.1063/1.3597790

Generation of plasmas in water: Utilization of a high-frequency, low-voltage bipolar pulse power supply with impedance control

Baroch P., Potocky S., Saito N.

Plasma Sources Science and Technology Vol. 20 ( 3 ) 2011.6

Language：English Publishing type：Research paper (scientific journal) Publisher：Plasma Sources Science and Technology

Presented work focuses on the investigation and characterization of plasma discharges generated in water by newly developed bipolar pulse power supply. The main aim of our work was to solve and overcome problems with intensive arc discharge transition when the discharge is ignited and maintained by a low output impedance pulse power supply. For this purpose a novel type of bipolar pulse power supply was developed and tested. It was found that two distinguished stable modes of discharges generated in the water can be realized. Effects of water conductivity, pulse frequency and initial water temperature on the discharge properties were investigated. Optical emission spectroscopy was employed to study plasma parameters of the discharge and the correlation between the data obtained from the optical emission spectroscopy and the chemical species measured in the water was carried out. © 2011 IOP Publishing Ltd.

DOI： 10.1088/0963-0252/20/3/034017

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